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Is there a performance difference between a for loop and a for-each loop?
... iterator or index variable
completely. The resulting idiom
applies equally to collections and
arrays:
// The preferred idiom for iterating over collections and arrays
for (Element e : elements) {
doSomething(e);
}
When you see the colon (:), read it as
“in.” Thus, the loop ab...
Test for equality among all elements of a single vector
I'm trying to test whether all elements of a vector are equal to one another. The solutions I have come up with seem somewhat roundabout, both involving checking length() .
...
ctypes - Beginner
...o testlib.so -fPIC testlib.c
# or... for Mac OS X
$ gcc -shared -Wl,-install_name,testlib.so -o testlib.so -fPIC testlib.c
Then, write a wrapper using ctypes:
testlibwrapper.py
import ctypes
testlib = ctypes.CDLL('/full/path/to/testlib.so')
testlib.myprint()
Now execute it:
$ python testlibwrap...
Batch File; List files in directory, only filenames?
...s is probably a very simple question, but I'm having trouble with it. Basically, I am trying to write a Batch File and I need it to list all the files in a certain directory. The dir command will do this, but it also gives a bunch of other information; I want it to list ONLY the file names and e...
Is the “struct hack” technically undefined behavior?
...rictly conforming with the C Standard, although it does seem to work under all known implementations. (Compilers which check array bounds carefully might issue warnings.)
The rationale behind the 'strictly conforming' bit is in the spec, section J.2 Undefined behavior, which includes in the list o...
Rename multiple files by replacing a particular pattern in the filenames using a shell script [dupli
...ho "$f" | sed s/IMG/VACATION/)"; done
In this example, I am assuming that all your image files contain the string IMG and you want to replace IMG with VACATION.
The shell automatically evaluates *.jpg to all the matching files.
The second argument of mv (the new name of the file) is the output of t...
How to get POSTed JSON in Flask?
...
First of all, the .json attribute is a property that delegates to the request.get_json() method, which documents why you see None here.
You need to set the request content type to application/json for the .json property and .get_jso...
Define css class in django Forms
... The only sane solution, I must say. Thank you!. Python code, and especially in form's definition, is the last place to put stuff for styling - these definitely belong to the templates.
– Boris Chervenkov
Nov 12 '11 at 23:09
...
Creating an abstract class in Objective-C
I'm originally a Java programmer who now works with Objective-C. I'd like to create an abstract class, but that doesn't appear to be possible in Objective-C. Is this possible?
...
How update the _id of one MongoDB Document?
I want update an _id field of one document. I know it's not a really good pratice. But with some technical reason, I need update it. If I try to update it I get:
...